Catheter having variable size guide wire lumen

ABSTRACT

A balloon catheter having a first balloon member and a second distal expandable member. The increased distal profile of the catheter with inflation of the second distal expandable member can deflect the distal-most end away from stent walls and edges. Another catheter has a distal region including longitudinal slits and a pre-stressed body configured to expand upon exposure to warm body fluids. Another catheter has a distal region including a first, inner tube disposed about a second, innermost tube. The inner and innermost tubes are secured at the distal-most end. The distal region includes longitudinal slits through the inner tube, thereby defining flaps between the slits. The innermost tube can be retracted relative to the inner tube disposed about the innermost tube, thereby causing the longitudinal flaps to expand outward, thereby increasing the maximum radial extent of the distal region. In yet another embodiment, a balloon catheter having a first guide wire tube is provided. A second guide wire tube is also provided, adapted to be received within the larger, first guide wire tube.

CROSS REFERENCES TO CO-PENDING APPLICATIONS

The present application is a continuation-in-part of U.S. Patent Ser.No. 09/034,421 filed Mar. 4, 1998 now U.S. Pat. No. 6,113,579, issuedSep. 5, 2000, entitled “CATHETER TIP DESIGNS AND METHODS FOR IMPROVEDSTENT CROSSING”.

FIELD OF THE INVENTION

The present invention is generally related to medical devices. Morespecifically, the present invention is related to intravascularcatheters having improved tips and guide wire lumens. The presentinvention includes catheters having an inflatable bulbous tip, a tippre-stressed to expand outward, an expandable tip, and an inner-mostguide wire tube disposed within an inner guide wire tube.

BACKGROUND OF THE INVENTION

Intravascular diseases are commonly treated by relatively non-invasivecatheter-based techniques such as percutaneous transluminal angioplasty(PTA) and percutaneous transluminal coronary angioplasty (PTCA).Catheter-based treatment and diagnostic techniques can also includeatherectomy, laser radiation, ultrasonic imaging along with others.These therapeutic techniques are well known in the art and typicallyinvolve the use of a catheter, such as a balloon catheter or catheterhaving some other therapeutic device located proximate a distal end ofthe catheter, with a guide wire, possibly in combination with otherintravascular devices. A typical balloon catheter has an elongate shaftwith a balloon attached proximate the distal end and a manifold attachedto the proximal end. In use, a balloon catheter is advanced over a guidewire such that the balloon is positioned adjacent a restriction in adiseased vessel. The balloon is then inflated and the restriction in thevessel is opened.

A more recent technique for treating intravascular diseases includes theuse of a balloon dilatation catheter to carry and place a stent withinthe lumen of the blood vessel at a stenosed area. The stent is agenerally cylindrical body with a lumen therethrough which isballoon-expanded when placed at the site of a lesion from a compressedconfiguration to an expanded configuration which physically prevents theblood vessel lumen from blocking over the length of the stent. The wallof the stent is preferably made from a metallic material and includes apattern of interconnected struts with interstitial spaces therebetweenwhich are open through the cylindrical wall. Stents of this design aredisclosed in U.S. Pat. No. 5,449,373, and in PCT publication WO96/03092, the disclosures of which are incorporated herein by reference.Catheters specifically designed to deliver such stents are disclosed inU.S. Pat. No. 4,950,227, the disclosure of which is also incorporatedherein by reference.

There are two basic types of balloon catheters used in combination witha guide wire, namely, over-the-wire (OTW) catheters andsingle-operator-exchange (SOE) catheters. The construction and use ofboth OTW catheters and SOE catheters are well-known in the art. Anexample of an OTW catheter may be found in commonly-assigned U.S. Pat.No. 5,047,045 to Arney et al., the disclosure of which is incorporatedherein by reference. An example of an SOE balloon catheter is disclosedin commonly-assigned U.S. Pat. No. 5,156,594 to Keith, the disclosure ofwhich is incorporated herein by reference.

PTA and PTCA catheters are preferably designed to optimize pushability,trackability and crossability. Pushability is defined as the ability totransmit force from the proximal end of the catheter to the distal endof the catheter. Trackability is defined as the ability to navigatetortuous vasculature. Crossability is defined as the ability to navigatethe balloon catheter across narrow restrictions in the vasculature.

The trackability of a particular catheter design is analyzed in terms ofthe trackability of the distal portion of the catheter, as this portionmust track the guide wire through small tortuous vessels to reach thestenosed area to be treated. A more flexible distal portion has beenfound to improve trackability. Further, in transitioning from a stiffproximal segment or portion of the catheter shaft to a more flexibledistal portion of the catheter shaft, it has been found that kinkingreadily occurs at the joint between the two shaft segments of differingflexibility. The increased flexibility of the distal section also makesthis portion of the catheter less able to be pushed from the proximalend of the catheter.

The crossability is related to the trackability of a particular catheterdesign in that crossability is affected by the flexibility of the distalsection of the catheter. Further, however, the crossability of thecatheter in the area of a tight lesion is effected by the design of thedistal tip of the catheter. The distal tip includes that region distalof the balloon which tracks the guide wire and at the distal-mostportion that portion which first must pass through a stenosed area.Thus, much effort has gone into designing tips with improvedcrossability such as those disclosed in co-pending application Ser. No.08/950,864, filed on Oct. 15, 1997 and entitled “OVER-THE-WIRE CATHETERWITH IMPROVED TRACKABILITY”, the disclosure of which is incorporatedherein by reference.

Although the above-referenced tip designs improve trackability andcrossability, it has been found that these tip designs can bedetrimental to the procedures utilized in placing and expanding a stent.More specifically, in the initial placement of a stent, the stent ispreloaded over the deflated balloon and the improved tip designsactually help in getting the stent in place across a lesion because thetip provides a leading edge through the lesion. However, it is commonprocedure to then expand the stent by inflating the balloon followed bydeflation of the balloon. The balloon catheter is then pulled back adistance over the guide wire and the placement of the stent evaluatedunder fluoroscopy. It is many times necessary to again move the balloondistally across the stent to perform a post or subsequent inflation ofthe balloon within the stent to properly seat the stent against thevessel wall. In these instances, the balloon catheter must be moveddistally over the guide wire to position the balloon across the stent.In these situations, the tip must first pass through the interior of thestent. It has been found that tips incorporating designs which improvethe crossability of the balloon catheter over a lesion can get caught onthe struts of the stent when passing therethrough and make it difficultto post dilate the stent. This is particularly true in a bend where theleading edge of the tip catches the outside wall of the curve becausethe guide wire tends to be pressed against the outside radius of thecurve while the distal-most tip of the catheter is biased that samedirection as it attempts to follow the curve.

The above described problems associated with tip designs which areoptimal for crossability of a lesion, but detrimental to crossing astent are also prevalent in subsequent treatment of lesions that aredistal of a stent within the same artery. To dilate a more distallesion, the balloon dilatation catheter to be utilized must first passthrough the lumen of a stent if one had been previously placed in theartery. The same problems with the tip catching on struts can occur.

Therefore, there is an unmet need for a catheter design whichincorporates a tip which is designed for crossing lesions but which isalso capable of being converted or modified to a second configurationwhich is suitable for crossing through the interior lumen of a stentwithout getting caught on a strut. The present invention, provides sucha tip design or tip design in combination with a guide wire design whichincludes means for reconfiguring the distal-most portion of a catheterto prevent strut and tip interaction which is detrimental to crossingthrough the lumen of the stent.

SUMMARY OF THE INVENTION

The present invention is directed to a catheter assembly having atherapeutic device mounted proximate a distal end thereof forintravascular treatment of the vessel at a location in the lumentherein. A preferred embodiment includes an over-the-wire ballooncatheter, which is described in detail herein, however, the balloondilatation catheter can include any known type of balloon catheterincluding a fixed wire catheter or a single operator exchange catheter.Further, the therapeutic device mounted proximate the distal end of thecatheter disclosed herein is an inflatable balloon, however, any otherknown therapeutic device can be mounted on the catheter and embody theinvention disclosed herein.

The over-the-wire balloon dilatation catheter generally includes anelongate tubular member having a proximal end and a distal end with aguide wire receiving lumen extending therethrough. The elongate tubularmember is coaxially disposed within an outer tubular member which alsoextends over a portion of the inner tubular member over a portion of itslength. The inner tubular member extends distally beyond the outertubular member, and an inflation lumen is formed in the annular spacebetween the two tubular members. A balloon having a proximal end and adistal end is mounted proximate the distal end of the catheter and formsan internal volume therein in fluid communication with the inflationlumen. In preferred embodiments, the proximal end of the balloon issealingly mounted proximate the distal end of the outer tubular memberand extends distally to a distal end which is sealingly connected to theoutside of the inner tubular member which extends beyond the outertubular member. The proximal end of the catheter includes a hub assemblywhich provides a guide wire receiving port which goes into the lumen ofthe inner elongate tubular member and an inflation port which is influid communication with the annular inflation lumen.

The catheter includes a tip portion which, in preferred embodiments, isthat portion of the catheter distal of the balloon and is generallyformed by a portion of the inner tubular member having the guide wirelumen extending therethrough. The tip is designed to initially beoptimum for aiding the catheter in tracking the guide wire and assistingin crossing a lesion to be dilated. Thus, the flexibility and shape ofthe tip are modified to aid in crossing. For example, the tip may benecked down relative to the proximal diameter of the inner or may beconically shaped having a decreasing outside diameter distally toreadily penetrate an obstructed vessel.

The various embodiments of the present invention are directed to tipdesigns and tip and guide wire designs which, in a first configuration,are optimal for crossing a lesion. A tip or tip and guide wirecombination in a second configuration is optimal for crossing a placedstent in that the tip portion does not catch on the struts in a stent,particularly a stent placed in a bend of a vessel.

In a first series of embodiments, the tip assembly includes means forreconfiguring the catheter tip from a first configuration for crossingan obstruction in the vessel lumen to a second configuration forcrossing a placed stent. One embodiment includes a severable distal tipsection, which is removed after treating the obstruction, but leaves aproximal portion of the tip which is more suited for crossing a stent.The remaining portion of the tip may be more bulbous in cross section orhave a larger lumen that is used in conjunction with a larger guidewire.

In an alternative embodiment, the distal-most tip can be reconfigured byrolling the distal-most portion back onto the inner tubular member sothat in a first configuration the tip may be passed through a lesion orobstruction, but in the second configuration, the folded back portionforms a more bulbous tip which will not catch on a strut as readily.Alternatively, the tip portion may be changeable from a straightconfiguration to a bent configuration which aids in crossing the stentwhen in a bent configuration.

In another embodiment, the inner tubular member may be slidable withinthe catheter or a sheath may be utilized which, when extended, providesa tip which readily crosses a lesion, but when retracted, the remainingtip portion is more bulbous or blunt for reducing the likelihood thatthis tip catches on the strut of a stent.

Finally, the tip of the catheter may include a distal-most portion whichis rotatably secured to the inner tubular member and extends distal ofthe balloon. The inside lumen of the rotatably secured tip can includeat least one helical protrusion on the lumen of the tip. When thecatheter is moved relative to the guide wire therethrough, frictionbetween the helical protrusion and the guide wire rotates the tip whichdecreases the likelihood that such tip will become caught on a strut ofa stent.

In a second series of embodiments, the configuration of the guide wireutilized in conjunction with the catheter tip assembly is shaped toprevent the distal tip of the catheter from catching on the stent strutwhen the guide wire is selectively positioned relative to the tip,wherein it deflects or pulls the tip away from the strut whilemaintaining the guide wire in contact with the stent. This can includedesigning the guide wire with a preshaped bend at a select location, orwith one or more helical coils which would be positioned within theinner lumen of the stent as the catheter crossed the stent.Alternatively, the guide wire can include a bulbous portion which, in aretracted portion, provides a more bulbous cross section on the distaltip to prevent the catheter tip from catching on a stent strut.

In another alternative embodiment, the guide wire can be caused tovibrate from the proximal end of the catheter so that the portion of theguide wire distal of the balloon vibrates in a preselected pattern whichassists in preventing or deflecting a catheter tip which may get caughton a stent strut.

The distal tip of the catheter may be designed with an inflatable cuffsurrounding a distal portion of the tip. The cuff can be in fluidcommunication with the guide wire lumen through a hole in the wall ofthe tip. Fluid may be injected down the guide wire lumen with sufficientpressure drop across the guide wire through the tip so that a portion ofthe inflation fluid fills the cuff and creates a more bulbous overalltip profile that would be less likely to catch on a stent strut whenpassing through the lumen of the stent.

The present invention can include a balloon catheter having a firstballoon and a second, distal inflatable balloon or cuff disposed distalof the first balloon. The second, distal balloon can be inflated toincrease the cross-sectional profile or maximum radial extent of thedistal-most region. Increasing the profile of the distal-most region canact to deflect the distal-most end away from a stent interior wall orend. In one embodiment, the first balloon interior is in fluidcommunication with the distal balloon interior. These embodiments havethe advantage of not requiring a separate inflation lumen for the distalballoon, which could otherwise require a tube or lumen extending theentire length of the catheter.

In one embodiment, a one-way valve is disposed between the first balloonand the distal balloon, acting to prevent rapid deflation of the distalballoon. In this embodiment, inflating the first balloon can alsoinflate the second balloon, whereupon the first balloon can be deflated,leaving the distal balloon still inflated. In another embodiment, acontrollable valve is disposed in the fluid space between the firstballoon and the distal balloon. The controllable valve can be opened,thereby allowing fluid to flow from the first balloon into the distalballoon. Fluid flow between the distal balloon and the first balloon canbe prevented by manipulation of the same valve. One valve is switchablebetween a first, open position, and a second, closed position. Anothervalve is biased to remain in a closed position, and can be manipulatedvia a pull wire to remain in the open position while the pull wire isretracted. In this embodiment, releasing the pull wire allows the valveto return to its closed state.

One balloon catheter incorporating the present invention includes adistal region including a tube having walls and a lumen therethrough.The tube has a plurality of slits through the walls and is formed of apre-stressed material, which has a first configuration having a firstcross-sectional profile or maximum radial extent and a secondconfiguration having a greater cross-sectional profile or maximum radialextent. The tube is pre-stressed so as to attain the secondconfiguration after insertion within the body. One preferred distalregion is formed of a shape memory material such as Nitinol or a shapememory polymer which, upon attaining body temperature, expands themaximum radial extent of the distal region. One catheter has a distalregion including flaps disposed within longitudinal slits, with theflaps curling outward when heated by warm body fluid. One catheter has adistal-most end having slits which terminate prior to the distal end. Inthis embodiment, the distal-most end can be cut by the treatingphysician, thereby exposing the longitudinal slits and allowing the tipto expand upon exposure to warm body fluids.

One catheter, according to the present invention, includes a distalregion having an inner tube and an innermost tube slidably disposedwithin the inner tube. The innermost tube can be affixed to the innertube at the distal-most end. In this embodiment, the distal region has aplurality of longitudinal slits defining flaps therebetween. Theinnermost tube can be retracted proximally, thereby pulling thedistal-most end of the innermost tube and the inner tube disposed aboutthe innermost tube. In response thereto, the flaps disposed between thelongitudinal slits bulge outward, thereby creating a greater maximumradial extent or cross-sectional profile of the distal region. Theoutwardly protruding distal region flaps can act to deflect thedistal-most end of the catheter away from stent walls and ends.

In another embodiment of the invention, a balloon catheter is providedhaving a first, inner guide wire tube having a first guide wire lumentherethrough. The catheter can include a manifold having a proximaltapered region disposed within. A second, smaller, inner tube having asecond, smaller guide wire lumen can also be provided. The second guidewire tube can have a proximal adapter having a taper adapted to beslidably received within the proximal region of the balloon cathetermanifold. The inner tube assembly thus provided can be disposed withinthe first guide wire tube and manifold, thereby providing a smallerguide wire lumen. In use, the balloon catheter can be used inconjunction with a first guide wire, where a first, larger guide wire isdesirable. When use of a second, smaller guide wire is desired, thefirst guide wire can be retracted. The inner tube assembly can then beadvanced through the catheter, with the second inner tube being thusdisposed within the first inner tube. With the second inner tube thusdisposed, a second, smaller guide wire can be advanced through th esecond inner tube and through the distal end of the balloon catheter.The second, smaller inner tube can provide improved support for thesmaller guide wire and can provide improved resistance against buckling.In one embodiment, the second, smaller inner tube has a lengthsufficient to extend distally from the distal end of the first,surrounding tube when the second tube is fully advanced within the firsttube.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects of the present invention and many of the attendantadvantages of the present invention will be readily appreciated as thesame becomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, in which like reference numerals designate like partsthroughout the figures thereof and wherein:

FIG. 1 is a cross-sectional view of a catheter showing a preferredembodiment of the present invention;

FIG. 2 is a partial cross-sectional view of a preferred embodimentdistal tip area of the catheter of FIG. 1, illustrating the tip formedfrom the inner;

FIG. 3 is a partial cross-sectional view of a second preferredembodiment of the distal tip area of the catheter of FIG. 1,illustrating the transition between the stiffer distal end of the innertube and the more flexible distal tip;

FIG. 4 is a cross section view of FIG. 1 taken along line 4—4;

FIG. 5 is a partial cross-sectional view of a first tip design whichincorporates a severable small profile distal portion and remainingblunt portion;

FIG. 6 is a partial cross-sectional view of an alternative embodimentsimilar to that of FIG. 5 which incorporates a severable conical tipportion with a remaining bulbous proximal tip portion;

FIG. 7 is a partial cross-sectional view of a tip design embodimentwhich incorporates a distal-most portion which folds back onto the tipto form a more bulbous cross section;

FIG. 8 is a partial cross-sectional view of a tip design which isdeflectable to a curved configuration to aid in crossing a placed stent;

FIG. 9 is a partial cross-sectional view of a tip design incorporatingan inner tubular member which is extendable to an extended positionwhich aids in crossing a lesion;

FIG. 10 is a partial cross-sectional view of the tip design of FIG. 9with the tubular member in a retracted position which leaves a blunterprofile for crossing a placed stent;

FIG. 11 is a partial cross-sectional view of a tip design including ahole through the wall thereof so that in a first configuration the tipis straight with the guide wire extending through the distal endthereof, while in a second configuration the guide wire protrudesdistally through the hole creating a bent distal tip portion forcrossing a stent;

FIG. 12 is a partial cross-sectional view which depicts an alternativetip design incorporating a bendable distal tip portion which in a bentposition as depicted aids in crossing a stent by rotating the catheter;

FIG. 13 is a partial cross-sectional view which depicts a guide wireconfiguration incorporating an offset bend or hump which contacts thewall of a stent and deflects the tip away therefrom;

FIG. 14 is a partial cross-sectional view which depicts a guide wireconfiguration incorporating multiple coils which deflect the tip awayfrom a placed stent when the tip is crossing over such coils;

FIG. 15 is a partial cross-sectional view which depicts a catheter tipdesign incorporating a rotatably secured distal-most portion which isrotated in conjunction with friction along the guide wire;

FIG. 16 is a schematic illustration of a catheter incorporating a guidewire that is vibrated from the proximal end;

FIG. 17 is a partial view which depicts an alternative guide wireconfiguration including a hump thereon with a tip positioned over aportion of the hump to prevent catching on the strut of a stent;

FIG. 18 is a partial cross-sectional view which depicts a guide wireconfiguration incorporating a bulbous distal portion on the guide wire;

FIG. 19 is a partial cross-sectional view which depicts the guide wireassembly of FIG. 18 in a retracted position which includes a tighttolerance with the bulbous portion which prevents the catheter tip fromcatching on a stent strut;

FIG. 20 is a partial cross-sectional view which depicts a tipconfiguration incorporating an inflatable cuff which inflates to providea generally bulbous profile that is less likely to catch on a stent;

FIG. 21 is a fragmentary, longitudinal, cross-sectional view of acatheter distal portion having an inflatable bulbous tip;

FIG. 22 is a fragmentary, longitudinal, cross-sectional view of acatheter distal portion and a perspective view of an inner tube having apre-stressed, longitudinally slit, distal portion prior to expansion;

FIG. 23 is a fragmentary, longitudinal, cross-sectional view of thecatheter distal portion of FIG. 22, illustrating the pre-stressed, slitdistal portion after expansion;

FIG. 24 is a fragmentary, longitudinal, cross-sectional view of anexpandable catheter distal portion including a tube having distal slitsand a tube slidably disposed within the tube and secured to the tubedistal end;

FIG. 25 is a fragmentary, longitudinal, cross-sectional view of theexpandable catheter distal portion of FIG. 24, illustrated after theinner tube has been retracted, radially expanding the distal portion;

FIG. 26 is a fragmentary, longitudinal, cross-sectional view of acatheter having a manifold and an inner guide wire tube; and

FIG. 27 is a fragmentary, longitudinal, cross-sectional view of aninnermost guide wire tube adapted to be slidably received within theinner guide wire tube and manifold of FIG. 26.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description should be read with reference to thedrawings in which like elements in different drawings are numberedidentically. The drawings, which are not necessarily to scale, depictselected embodiments and are not intended to limit the scope of theinvention.

Examples of constructions, materials, dimensions, and manufacturingprocesses are provided for selected elements. All other elements employthat which is known to those skilled in the field of the invention.Those skilled in the art will recognize that many of the examplesprovided have suitable alternatives which may also be utilized.

Referring now to the drawings, FIG. 1 is a cross-sectional view of anover-the-wire balloon catheter showing a preferred embodiment of thepresent invention. The balloon catheter 20 includes a shaft assembly 22and a balloon assembly 24 connected proximate its distal end. Aconventional OTW-type manifold assembly 26 is connected to the proximalend of the shaft assembly 22. The shaft assembly 22 includes an innertube 28 having a proximal end 30 and a distal end 32. The proximal endof the shaft assembly 21 extends into the manifold assembly 26adhesively bonded to the shaft assembly 22. A polyurethane strain relief23 is snap-fit to the manifold assembly 26, and the shaft assembly 22extends into the manifold assembly 26 through the polyurethane strainrelief 23. An outer tube 34 is coaxially disposed about the inner tube28 to define an annular inflation lumen 37.

The balloon assembly 24 includes a balloon body portion 36 with aproximal balloon waist 38 and a distal balloon waist 40. The proximalballoon waist 38 is connected to the outer tube 34 near its distal endby means of an adhesive 44. The distal balloon waist 40 is connected tothe inner tube 28 near its distal end 32 by means of an adhesive bond 48such that the interior of the balloon 46 is in fluid communication withthe annular inflation lumen 37.

A radiopaque marker band 50 is adhesively secured with cyanoacrylateadhesive to the inner tube 28 at a point underneath the balloon body 36.Alternatively, the marker band may be swaged onto the outer surface ofthe inner. The inner tube 28 defines a guide wire lumen 54 whichprovides a passage for a guide wire (not shown). The outer tube 34defines an annular inflation lumen 37 which is in fluid communicationwith the interior of the balloon 46.

As previously stated, the catheter of the present invention preferablyincludes an outer tube having a relatively stiff proximal outer section,a mid-shaft section of lesser stiffness, and a tapering distal outersection of the least stiffness. The progressive arrangement of moreflexible materials as the catheter proceeds distally provides an optimallevel of pushability and trackability to navigate tortuous vasculature.The flexibility of the segments of the outer tubular member were testedutilizing a Gurley bending resistance tester, Part No. 4171-DT, asmanufactured by Precision Instruments, Troy, N.Y. The apparatus consistsof a balanced pendulum or pointer which is center-pivoted and can beweighted at three points below its center. The pointer moves freely inboth the left and right directions. A sample of specific size isattached to a clamp, which in turn is located in one of severalpositions on a motorized arm which also moves left and right. During thetest, the sample is moved against the top edge of the vane, moving thependulum until a sample bends and releases it. The test is run in twosteps, first to the left and then to the right. The scale reading ismeasured in each direction and the results are averaged. The instrumentprovides a relative flexibility measurement between the components ofthe outer tubular member as detailed below to achieve improvedtrackability and pushability.

The outer tube 34 has a relatively stiff, proximal outer section 56 witha proximal end 60 and a distal end 62. The proximal outer tube may bemade of nylon, a polyamide, such as DURETHANE available from Bayer, aDURETHANE braid, CRISTAMID braid or polyetheretherketone (PEEK) braid. Apreferred embodiment of PEEK or CRISTAMID braid is a variable PIC tube,wherein said PIC varies from about 30 to 100 PIC to give varyingflexibility over the length of the proximal outer tube. The PICpreferably varies from about 50 to about 80. The braiding material inthe PEEK or DURETHANE (polymer) braid may be made from stainless steel,or Nitinol (nickel titanium alloy). This proximal outer section 56 willhave an outside diameter ranging from 0.040 inches to 0.045 inches witha wall thickness ranging from 0.0028 inches to 0.0044 inches. Theproximal outer section has a preferred Gurley value of about 500 toabout 1300 over its length. A preferred range is about 800 to about1200. FIG. 4 illustrates a cross section view of the proximal outersection having braid material as taken along 4—4 of FIG. 1. The braidincludes an inner layer 100, a braid layer 101 and an outer layer 102.

A midshaft section 58 with a proximal end 64 and a distal end 66 extendsdistally from the distal end of the proximal outer section 62. Themidshaft section 58 has a stiffness less than that of the proximal outersection 56. The midshaft section 58 is preferably made from a polyamide,such as CRISTAMID available from Elf Atochem, having a durometer ofabout 81D. A preferred Gurley value for the midsection is about 350 toabout 500, with a range of 400 to 450 preferred. This midshaft section58 will have an outside diameter ranging from 0.040 inches to 0.045inches with a wall thickness ranging from 0.0028 inches to 0.0044inches.

The distal end of the proximal outer section 62 is joined to theproximal end of the midshaft section 64 with a urethane adhesive bond ora thermal weld. A distal outer section 68 having a proximal end 70 and adistal end 72 extends distally from the distal end of the midshaftsection 66 to the distal end of the outer tube 44. This distal outersection 68 is more flexible or has less stiffness than both the proximalouter section 56 and the midshaft section 58. The outer diameter of thedistal outer section 68 will taper from about 0.045 inches at theproximal end 70 to 0.030 inches at the distal end 72. This distal outersection 68 is made of polyether block amide (PEBAX) with a durometer of70D. The tapered distal outer section preferably has a Gurley value ofabout 70 to about 90 at its proximal end and about 15 to about 40 at itsdistal end. Thus, the distal end of the distal outer section 72 willexhibit less stiffness than the proximal end of the distal outer section70. The distal end of the midshaft section 66 is joined to the proximalend of the distal outer section 70 with a urethane adhesive bond or athermal weld.

A Nitinol braid insert 74 with a length of about 1.0″ is placed withinthe proximal end of the distal outer section 70 to provide strain reliefand reduce kinkability at the midshaft/distal outer section junction.This Nitinol braid 74 has a 0.001″×0.005″ ribbon.

The inner tube 28 is made of polyethylene such as Marlex HDPE. At theproximal end of the inner tube 30, the inner tube 28 has an outsidediameter ranging from 0.024 inches to 0.026 inches and preferably about0.025 inches, with the inner tube 28 having an inside diameter rangingfrom 0.018 inches to 0.0195 inches for a 0.014 inch guide wire for whichthis lumen is designed to be compatible with. The inner tube 28 has awall thickness ranging from 0.0026 inches to 0.004 inches and preferablyabout 0.0032 inches. The outside diameter to wall thickness ratio mustbe sufficiently small to minimize the propensity of kinking.

As the inner tube 28 extends distally through the junction area betweenthe distal end of the proximal outer section 62 and the proximal end ofthe midshaft section 64 of the outer tube 28, both the inner and outerdiameters of the inner tube 28 will taper from wider diameters tonarrower diameters. Likewise, at the distal end of the inner tube 32,both the inner and outer diameters of the inner tube 28 will once againtaper from wider diameters to narrower diameters as the tube extendsdistally.

As illustrated in FIG. 2, in one preferred embodiment, a distal tip 76is formed on the distal end of the inner tube 32 where the inner tube 28distally tapers from a larger outer diameter to a smaller outerdiameter. The distal balloon waist 40 is attached to the distal tip 76through a urethane adhesive bond at a bonding area. The area just distalof the distal waist bond is backfilled with adhesive 43 to provide asmooth transition. The adhesive coating provides for improved adhesionbetween dissimilar substrates.

The proximal catheter shaft portion is preferably about 35 to 45 inchesin length with a preferred length of 42 inches. The midshaft section ispreferably about 1 to about 3 inches in length with a preferred lengthof 2 inches. The distal outer section having the most flexibility ispreferably about 8 to about 12 inches in length with a preferred lengthof about 10 inches.

In another preferred embodiment, as shown in FIG. 3, a polyethylenedistal tip 80 of durometer between about 45D and 65D, preferably about55D is heat welded or bonded to the distal end of the inner tube 32 witha durometer of about 63-65D, and the distal balloon waist 40 of theballoon is adhesively bonded to both the inner and the tip extendingtherefrom. As shown in FIG. 3, the joint 41 between the inner and thetip is located under the distal waist of the balloon. The outer diameterof the polyethylene distal tip 80 distally tapers from a larger outerdiameter to a smaller outer diameter.

In another preferred embodiment, incorporating a soft tip as describedabove, the last ½ to 1 mm of the tip at its distal end is made of adifferent material from the tip material to form a tip extension. Inparticular, the last ½ to 1 mm is made from a material which is moredurable relative to the softer tip material. In particular, the moredurable material will resist deforming or tearing when in use, such astracking tortuous anatomy or through a placed stent. For example, thislast ½ to 1 mm may be manufactured from Marlex high density polyethylenehaving a 63D durometer which improves the integrity of the tip portionat its distal-most end 81.

As previously discussed with respect to FIGS. 2 and 3, the tip design ofthe present catheter includes features which assist in the tip portionof the balloon catheter crossing a lesion or obstruction in a lumen.This can include a conically shaped tip which reduces an outsidediameter, or has an area of reduced outside diameter. This can alsoinclude utilizing materials which are relatively soft to improve thetrackability. These designs, however, are not optimum for the tip tocross through the inside lumen of a stent having struts thereon. Thetip, as depicted in FIGS. 2 and 3, tend to catch on the struts of thestent, particularly if the guide wire that the tip is tracking is in acurve or bend in the vessel lumen. In such bend, the tracking tip tendsto bias toward the outward edge of the bend where it can readily catchon the stent strut. The present disclosure is directed to tip and tipand guide wire combination designs which include means for reconfiguringthe catheter tip so that it more readily crosses a placed stent.

Referring now to FIG. 5, a first embodiment incorporating a means forreconfiguring the distal tip of the catheter from a first configurationfor crossing vessel lumen obstructions to a second configurations forcrossing a placed stent is depicted. The embodiment disclosed includesan inner tubular member 110 extending through a balloon 112 having adistal waist 114. The tubular member 110 extends distally through theballoon waist 114 and protrudes distally therefrom to form a tip 116.The tubular member 110 has a lumen 111 extending therethrough forreceiving a guide wire (not shown). The tip 116 includes a distalportion 118 having a reduced inside and outside diameter relative to theproximal portion of the tubular member 110. In a first configuration forcrossing a vessel lumen obstruction, the tip is configured as depictedin FIG. 5. To reconfigure the tip for crossing a stent, the tip issevered proximal of the necked down portion of the tip 118, as forexample, at 119. To facilitate removal of a portion of the tip, a lineof weakened strength can be included, such as a perforation to aid inremoving such portion. In the second configuration, the distal-mostportion of the inner tubular member 110 is a distal end 119, which asdepicted in FIG. 5, is of greater cross section and more blunt than theprior configuration. This aids in passing by the struts of the stent andcan be further assisted by using a larger diameter guide wire whichprovides additional stiffness through the stent lumen.

In a preferred embodiment of the tip of FIG. 5, the severable tip 118has a reduced lumen diameter, preferably sized for use with a guide wirehaving a diameter of 0.014 inches, while the lumen proximal thereof hasa diameter sized for use with a 0.018 inch guide wire. This option isuseful even in non-stent crossing applications, for example, any time astiffer wire is necessary.

Referring now to FIG. 6, an alternative embodiment of the tip design ofFIG. 5 is depicted. With this design, the balloon also includes proximalwaist 114 and inner tubular member 110 extending therethrough. A guidewire lumen 111 runs through the inner tubular member 110. In a firstconfiguration, the tip design of FIG. 6 includes a distal tip portion118 which is generally conical along the outside diameter for morereadily penetrating an obstruction in a vessel lumen. The tip design isconvertible or reconfigurable to a second configuration which morereadily crosses a stent by severing the distal tip portion 118 at anarea such as 120. Proximal of this point of severability, the tipincludes a generally bulbous portion 121. The bulbous cross section ofthe remaining tip portion is designed to pass over a stent strut withoutcatching the leading edge.

Referring now to FIG. 7, a cross section of a distal-most portion of theinner tubular member forming the tip 116 is depicted with the guide wirereceiving lumen 111 extending therethrough. With this embodiment, themeans for reconfiguring the catheter tip comprises a soft distal-mosttip portion 122 which is configured to roll back onto the inner tubularmember 116 at its distal-most end to form a bulbous leading edge 123that aids in crossing a stent without catching on a strut. Thedistal-most tip portion 122 can be skived longitudinally to aid inrolling back the tip when in contact with a stent.

Referring now to FIG. 8, another alternative embodiment incorporatingmeans for reconfiguring the catheter tip is disclosed. The embodiment ofFIG. 8 includes an inner tubular member 110 having a lumen 111 extendingtherethrough for receiving a guide wire. A tip 116 is formed distal ofthe distal waist 114 of the balloon 112. With this embodiment, a firstconfiguration, not shown, would include a straight tip 116 when theguide wire is extended therethrough. The guide wire can then beretracted proximally and the tip can be prebiased to reconfigure to abent configuration such as that depicted in FIG. 8. The blunt end 123 ofthe bent section of the tip more readily crosses a stent withoutcatching on a strut since the leading edge of the tip is no longer ableto contact the strut and catch thereon.

Referring now to FIGS. 9 and 10, another alternative embodiment of a tipdesign is disclosed. With the tip design of FIGS. 9 and 10, the meansfor reconfiguring the catheter tip include an inner tubular member 110extending through the balloon 112 and distal waist 114. However, theoutside surface of the inner tubular member is not adhesively secured tothe distal waist of the balloon, but rather slidably receivedtherethrough. In a first configuration, as depicted in FIG. 9, the innertubular member 110 is extended distally to form the tip 116 which issuitable for crossing an obstructed lumen. FIG. 10 depicts theembodiment of FIG. 9 in the reconfigured mode, wherein the inner tubularmember 110 is retracted proximally to leave a more blunt profile on thedistal-most portion of the catheter which aids in crossing a stent. Inorder for the inner tubular member 110 to be utilized in theabove-described manner, the area of engagement 130 of the balloon waist114 with the exterior surface of the inner tubular member 110 must forma seal therebetween so that the inflation fluid does not substantiallyleak therethrough. This can be accomplished based on tolerances orprebiasing the distal waist of the balloon. Alternatively, an O-ringtype seal could be included in the distal waist of the balloon or on theexterior surface of the inner tubular member as positioned under thedistal waist of the balloon.

Referring now to FIG. 11, another alternative embodiment of a distal tipdesign is depicted. In the embodiment of FIG. 11, the inner tubularmember 110 includes a distal portion 116 which extends beyond the distalwaist 114 of the balloon 112. The portion of the inner tubular memberextending beyond the distal waist forms the tip. The tip of thisembodiment includes a hole 132 through the side wall at a positionproximal of the distal-most end 134 of the tip 116. In a firstconfiguration, which is not shown in FIG. 11, the guide wire 136 extendsthrough the distal end of the tip 116 and holds the tip portion in astraight configuration which is more suitable for crossing anobstruction in a lumen. The tip is reconfigured by passing the guidewire through the hole 132 in the side wall so that the portion of thetip distal of the hole forms a bent configuration which more readilycrosses a placed stent.

Referring now to FIG. 12, an alternative embodiment of a distal tip 116is depicted. With the embodiment of FIG. 12, the distal tip 116 is firstconfigured as a straight tip having a guide wire extending therethrough.The tip is designed to be reconfigured to a bent tip which is bent withan acute angle from straight, as for example, a 45° angle from straight.The tip is designed to be held at this angle, as for example byincorporating metal strips or a coil or braid which remains reconfiguredwhen bent. With the tip bent at an acute angle from straight, the tip isconfigured for crossing a stent, in that if resistance to movingdistally is encountered in the stent, the catheter can be rotated fromthe proximal end so that the distal-most tip 134 deflects away from thestent wall and should proceed through the stent as rotated. The stentwill then contact a portion of the tip 116 which is proximal of thedistal-most tip 134.

Referring now to FIG. 15, another alternative embodiment of a tipconfiguration is depicted. The tip 116 of inner elongate tubular member110 includes a distal-most portion 150 rotatably secured to the distalend 151 of the inner elongate tubular member 110. The distal-mostportion 115 is configured to rotate in response to axial movement of theelongate tubular member 110 relative to a guide wire placed in the lumen111 therethrough. In a preferred embodiment, the lumen of thedistal-most tip portion 150 includes at least one helical projection 152therein which causes the rotational movement of the distal-most tipportion 115 due to friction with the guide wire when moved axiallyrelative thereto. The slight rotation of the tip as it passes throughthe lumen of the stent is believed to aid in preventing the distal-mosttip portion from catching on a stent strut while not being detrimentalto the tip's ability to cross a lumen obstruction.

Referring now to FIG. 20, another alternative embodiment of altering thetip configuration on the catheter assembly is disclosed. The embodimentof FIG. 20 includes an inflatable cuff 160 which is secured to theoutside diameter of the distal tip portion 116. The cuff is inflatablefrom a first position wherein the cuff is flat on the outside diameterof the tip 116 to an inflated position which forms a more bulbousprofile which is more adequate for crossing a stent. The tip in bothconfigurations is depicted in FIG. 20. The cuff may be inflated orexpanded via a hole through the wall of the tip 116 by passing fluiddown the guide wire lumen with the guide wire therein. The guide wirecan be sized, especially in the distal portion, so that the resistanceto fluid flow out the distal end of the catheter forces some of thefluid into the expandable cuff 160.

Referring now to FIGS. 13, 14 and 16-19, another type of tip and guidewire design is disclosed which incorporates a guide wire having meansfor deflecting the tip away from the interior wall of the stent to aidin passing through the lumen of the stent. By deflecting the distal-mostor leading edge of the tip, away from the stent wall, catching on strutsis prevented. Each of the various embodiments discussed below functionin this manner.

Referring now to FIG. 13, a guide wire 136 is depicted extendingdistally from the distal tip 116. The guide wire has preformed thereinan offset or hump 170. The distal tip 116 can be positioned justproximal of the offset 170 so that when the tip and guide wire are movedtogether around a bend in a vessel which contains a stent therein, thehump 170 contacts the stent wall and deflects the tip 116 away from thestruts.

In an alternative mode of operation, as depicted in FIG. 17, the guidewire also includes a hump or bend 170. However, with this embodiment,the tip 116 is positioned so that a distal-most portion 172 ispositioned partway around the bend or hump 170. As shown in FIG. 17,this forms a bend in the distal end of the tip 116 which, when moveddistally together with the guide wire, would not contact the struts on astent. Although a single hump or bend is depicted, it is recognized thatmultiple humps or bends can be included in the same or differing planes.

Referring now to FIG. 14, another alternative guide wire designincorporating means to deflect the tip away from the stent wall isdepicted. The guide wire 136 includes a plurality of helical coils 175.The outside diameter of the helical coils is greater than the diameterof the guide wire lumen so that the tip 116 is deflected away from thestent wall when both are moved distally through a stent lumen.Alternatively, the coils can be designed so that they straighten inresponse to the tip passing thereover. When straightening the coils, thetip will be deflected with each pass based upon the bias of the coil andwill deflect the tip away from the stent wall. With this embodiment, thecoiled portion of the guide wire would generally include a length whichis equal to or greater than the length of the stent through which thecatheter must pass.

Referring now to FIG. 16, the catheter 20 of FIG. 1 is depictedschematically. The catheter includes a tip 116 and a guide wire 136which extends distally beyond the distal end of the tip. Means forimparting vibration 180 is included on the proximal end of the catheterand connected to the guide wire. By imparting vibration to the guidewire, it is believed that the distal end of the guide wire will vibrateas the catheter tip 116 passes thereover. The vibrational pattern isdepicted in phantom 138 in FIG. 16. It is believed this vibration willcause the catheter tip 116 to deflect away from the stent wall 140 asdepicted.

Another guide wire embodiment is depicted in FIGS. 18 and 19. The guidewire 136 includes a portion of expanded diameter 190. In an extendedposition, the gap between the guide wire lumen and the outside surfaceof the guide wire allows for easy tracking of the guide wire thereover.As depicted in FIG. 19, when the guide wire 136 is in a retractedposition, the tolerance between the guide wire lumen and the expandedportion 190 of the guide wire 136 is extremely tight tolerance so thatthe tip does not fit loosely on the guide wire. This will cause the tipto more closely track the guide wire and prevent it from deflecting andcatching on a stent strut.

Referring now to FIG. 21, a balloon assembly 200 is illustrated,including a balloon body 202 a distal tip 220, and a distal-most end222. Balloon assembly 200 further includes a distal inflatable cuff orballoon 206 including a balloon wall or envelope 205 and a ballooninterior 207. Distal balloon 206 has a first, uninflated configurationindicated at A, and a second, inflated configuration indicated at B. Inone embodiment, distal inflatable balloon 206 imparts a bulbous shape todistal tip 220. Balloon 206 can be formed from balloon envelope materialadhered to the distal tip region. Balloon body 202 includes a ballooninterior 204, and in the embodiment shown, a balloon interior wall 208.Balloon assembly 200 includes a distal balloon inflation lumen 210 and aguide wire lumen 218 defined by an inner tube 216. In the embodimentillustrated, balloon interior 204 is in communication with distalballoon inflation lumen 210 through a first opening 212, and distalballoon inflation lumen 210 is in communication with distal inflatableballoon interior 207 through a second opening 214. In one embodiment,distal balloon inflation lumen 210 is defined by a tube extendingthrough balloon body 202 and including, for example, balloon interiorwall 208. In one embodiment, balloon body 202 interior 204 is in fluidcommunication with distal inflatable balloon 206, such that inflatingballoon 202 inflates distal inflatable balloon 206.

In one embodiment, a valve acts to allow inflation of distal inflatableballoon 206 while inflation fluid is provided under pressure, yet doesnot allow exit of inflation fluid from distal inflatable balloon 206 inthe absence of inflation fluid pressure. In the embodiment illustratedin FIG. 21, a valve plug 225 is disposed at the distal end of a valvecontrol wire 227 and positioned near a valve seat 224. Valve plug 225can be retracted to allow fluid flow from balloon interior 204 intodistal balloon interior 206. Valve plug 225 can be advanced againstvalve seat 224 to prevent fluid flow between balloons 202 and 206. Inone embodiment, valve plug 225 is distally biased, for example with aspring, to seat against valve seat 224. Valve plug 225, when retracted,allows balloon 202 to be inflated substantially simultaneously withdistal balloon 206. Valve plug 225, when seated, allows balloon 202 tobe deflated while distal balloon 206 remains inflated.

In one embodiment, a one-way valve allows infusion of inflation fluidunder pressure into distal inflatable balloon 206, yet allows onlygradual deflation of distal inflatable balloon 206, back through theone-way valve. In the aforementioned embodiment, the valve termed aone-way valve can actually allow flow in a second direction, albeit at amuch slower rate than in a first, primary direction. In one embodiment,distal inflatable balloon 206 is configured so as to allow a gradualdeflation of the balloon in the absence of infusion fluid supplied underpressure.

As can be seen from inspection of FIG. 21, the bulbous shape of distalinflatable balloon 206, when inflated, can act to deflect distal-mostend 222 away from the edge or interior wall of a stent.

In use, in embodiments having a separate inflation lumen for the distalinflatable balloon, the balloon assembly can be advanced near a stent.The distal inflatable balloon can be inflated to attain a larger orbulbous profile, and distal-most end 222 is then further advancedthrough the stent. After distal-most end 222 has been advancedsufficiently through the stent, the distal inflatable balloon can eitherbe left inflated, deflated, or allowed to deflate at a controlled ratethrough a controlled deflation means such as a permeable membrane or asmall escape orifice. In embodiments having a separate distal ballooninflation lumen, one method utilizes the separate inflation lumen forboth inflation and deflation of the distal inflatable balloon.

In use, in embodiments having a shared fluid space between balloon body202 and distal inflatable balloon 206, balloon body 202 and distalinflatable balloon 206 are both inflated prior to advancing distal-mostend 222 into a stent to be crossed. In one method, after distal-most end222 has been advanced sufficiently into stent, balloon body 202 anddistal inflatable balloon 206 are allowed to deflate or are activelydeflated by removing inflation fluid, allowing balloon body 202 to moreeasily enter the stent. In embodiments having a shared fluid spacebetween balloon body 202 and distal inflatable balloon 206 and furtherhaving a one-way valve and controlled escape of inflation fluid fromdistal balloon 206, both balloon body 202 and distal balloon 206 can beinflated before advancing distal-most end 222 into a stent. Afterdistal-most end 222 has been advanced sufficiently into the stent,inflation fluid pressure may be removed, allowing balloon 202 todeflate, yet allowing distal balloon 206 to remain inflated. In onemethod, distal balloon 206 deflates at a controlled rate by escape ofinflation fluid through a means for inflation fluid escape such as asemi-permeable membrane or an escape orifice in distal balloon 206. Theuse of a one-way valve in the shared fluid space between balloon body202 and distal balloon 206 can eliminate the need for a separateinflation lumen or tube extending the entire length of the catheter.This can reduce the overall profile and complexity of the catheter. Inparticular, use of a shared fluid space allows distal inflatable balloon206 to be effectively inflated using fluids supplied to distal balloon202.

Referring now to FIG. 22, a balloon assembly 230 is illustratedincluding a balloon distal waist 232, an adhesive area 234, and an innertube 240. Inner tube 240 includes a tube wall 244 and a distal portion231, and terminates distally in a distal-most end 238. In the embodimentshown, a plurality of longitudinal slits 236 extend through tube wall244 near distal-most end 238, but not through an unslit distal region241. Slits 236 define a plurality of flaps 246 therebetween. Unslitregion 241 extends distal of slits 236, allowing an unslit distal-mostend to be presented. In this embodiment, unslit region 241 can be cuttransversely and removed, thereby presenting slits 236 at thedistal-most end. In FIG. 22, distal-most end 238 is shown in a firststate having a cross-sectional profile and a radial extent substantiallythat of tube 244, and including unslit region 241. In one embodiment,distal portion 231 is formed of a shape memory material, such as Nitinolor a shape memory polymer well known to those in the art.

Referring now to FIG. 23, balloon assembly 230 is shown in a secondstate having unslit region 241 removed and distal portion 231 having anincreased cross-sectional profile and radial extent relative to distalportion 231 as shown in FIG. 22 and relative to the majority of thelength of inner tube 244. FIG. 23 illustrates flaps 246 having a curledand outwardly extending configuration. Flaps 246, by having an increasedradial extent relative to tube 244, present an increased distal-mostprofile when approaching a stent.

The increased distal-most profile presented by flaps 246 acts to preventdistal-most end 238 from catching in a stent to be crossed. The flaps246, especially when having a number of relatively floppy or flexiblecomers 248, present a distal-most end having less resistance whencatching on a stent. In particular, the floppy distal-most comers 248tend to bend back toward the balloon when caught on a stent wall oredge. Thus, balloon assembly 230 can be advanced distally through astent even when distal-most comers 248 become engaged with a stent.Similarly, the increased slit width caused by curling of flaps 246decreases the strength of distal portion 231 relative to a distalportion having no slits. The relatively weakened distal portion as awhole thus presents a more flexible or floppy distal region when engagedwith a stent wall or edge, allowing balloon assembly 230 to be furtheradvanced distally, even when distal portion 231 is engaged. In thisscenario, distal portion 231 flaps 246 are expected to bend proximallytoward the balloon and then curl distally once balloon assembly 230 isfurther advanced, and the engagement between flaps 246 and the stentends when the flaps are freed of the stent.

In use, in embodiments having a distal-most end that includes no slitsat the distal-most end, the balloon assembly and catheter can be used ina normal fashion until difficulty in crossing a stent is encountered orexpected. At this point, the catheter can be retracted and the unslitportion of distal portion 231 cut, thereby exposing a distal portionhaving slits extending through to the most-distal end. The catheter canthen be advanced to the stent to be crossed. Flaps 246, having beenformed of a shape memory material, can attain the outward configurationillustrated in FIG. 23 after sufficient exposure to body temperature.

Referring now to FIG. 24, a balloon assembly 250 is illustrated,including a balloon distal waist 252, an inner tube 254 having a distalregion 260, a distal-most region 262, and a distal-most end 266. Innertube 254 includes an inner tube wall 256 having a plurality oflongitudinal slits 264 extending through distal region 260 and defininga plurality of flaps 270 therebetween. In a preferred embodiment, aninnermost tube 258 is slidably disposed within inner tube 254. Innertube 258 is preferably joined to inner tube 254 in distal-most region262, for example, by adhesive application or bonding. In a preferredembodiment, inner tube 254 and innermost tube 258 are slidably disposedwithin much of distal region 260, but fixed relative to one another indistal-most region 262. In a preferred embodiment, distal region 260 isformed of a flexible polymeric material such as high densitypolyethylene. Innermost tube 258 preferably has a guide wire lumen 268disposed therethrough. In an alternate embodiment, innermost tube 258can be replaced by an innermost shaft or wire-like member not having alumen within.

Referring now to FIG. 25, balloon assembly 250 of FIG. 24 is furtherillustrated in a second configuration having an increasedcross-sectional profile or increased radial extent. Retracting innermosttube 258 relative to inner tube 254 causes flaps 270 to expand theradial extent of distal region 260. In use, balloon assembly 250 can beadvanced to a location near a stent. Innermost tube 258 can be retractedwithin inner tube 254, thereby causing distal region 260 to expand asillustrated in FIG. 25. The increased radial extent and cross-sectionalarea of distal region 260 can act to deflect distal-most end 266 fromstent walls and edges. Once distal-most end 266 has been sufficientlyadvanced, innermost tube 258 can be advanced relative to inner tube 254,thereby allowing flaps 270 to resume the smaller profile illustrated inFIG. 24.

Referring now to FIG. 26, a balloon catheter 300 is illustrated having amanifold 308, a shaft 309, and a balloon assembly 302. Shaft 309includes a first inner tube or guide wire tube 304 including a firstlumen 306 within terminating in a distal orifice 307. Manifold 308includes a proximal tapered region 310 including a tapered lumen 311therein. Manifold 308 includes a threaded region 314 connecting manifold308 to an interconnect device 312. In one embodiment, first inner tube304 has an inside diameter of about 0.035 inches. In another embodiment,first inner tube 304 has an inside diameter of about 0.018 inches.

Referring now to FIG. 27, an inner tube assembly 320 is illustratedhaving a second inner tube or guide wire tube 316 and a second guidewire lumen 318 disposed therein. Inner tube assembly 320 includes aproximal adapter 322 having a proximal lumen 324 disposed within andbeing in fluid communication with second guide wire lumen 318. Secondinner tube 316 is sized to be received within first guide wire tube 304.Proximal adapter 322 is sized to be received within proximal taperedportion 310 of manifold 308. In one embodiment, second inner tube 316has an inside diameter of about 0.014 inches. In one embodiment, secondinner tube 316 has a length adapted to the length of first inner tube304, such that when fully advanced into first inner tube 304, secondinner tube 316 extends distally from first inner tube distal orifice307.

In use, balloon catheter 300 may be advanced within the vasculature of apatient, bringing balloon assembly 302 to position near a target site.At that point, it may be desirable to further advance balloon assembly302 to a more distant region of the vasculature and/or a more occludedregion of the vasculature. This more distant and/or more occluded regionmay suggest the use of a smaller guide wire. Use of the smaller guidewire would aid in crossing a tight lesion or attaining position within atortuous vascular region, but would be substantially smaller than theinside diameter of first guide wire lumen 306. At that point in time,the treating physician may wish to provide a second, smaller guide wire.This second smaller guide wire would receive improved support from aguide wire tube having a smaller inner diameter. The first guide wirecan then be retracted from balloon catheter 300, and inner tube assembly320 advanced distally into first guide wire lumen 306 of ballooncatheter 300. With second inner tube 316 disposed within first innertube 304, a smaller, second guide wire lumen 318 is provided. A second,smaller guide wire can be advanced through second guide wire lumen 318until a location distal of balloon assembly 302 is reached. The second,smaller guide wire can be further advanced to the target site. Thesecond, smaller guide wire can receive improved support against bucklingby smaller, second guide wire lumen 318 provided within second innertube 316.

In one embodiment, the second inner tube can extend distally from thefirst, surrounding, inner tube. The second inner tube can have the axialposition adjusted such that the length of second tube extending distallyfrom the first tube is varied. This can provide a distally protrudinginner most tube, either with or without a guide wire disposed within.Distally advancing the inner most tube can provide a small profile whichcan be advantageous when crossing a constricted region. Proximallyretracting the inner most tube can present a larger profile whendesired.

In particular, it is recognized that the catheters of the presentinvention can include over-the-wire catheter designs, fixed wirecatheter designs and single operator exchange catheter designs withinthe scope of the present disclosure.

Numerous advantages of the invention covered by this document have beenset forth in the foregoing description. It will be understood, however,that this disclosure is, in many respects, only illustrative. Changesmay be made in details, particularly in matters of shape, size, andarrangement of parts without exceeding the scope of the invention. Theinvention's scope is, of course, defined in the language in which theappended claims are expressed.

What is claimed is:
 1. A catheter tip assembly for crossing both vessel lumen obstructions or placed stents, said tip assembly comprising: an elongate tubular member having a proximal end, a distal end, and a guide wire receiving lumen and an inflation lumen extending therethrough; an inflatable balloon disposed proximate said distal end of said elongate tubular member, wherein a distal portion of said elongate tubular member extends distally beyond said inflatable balloon to form a catheter tip which defines a first tapered leading edge for crossing vessel lumen obstructions or placed stents, wherein said inflatable balloon has an interior in fluid communication with said inflation lumen; and a distal inflatable tip balloon disposed distal of said inflatable balloon, wherein said distal inflatable tip balloon has an interior in fluid communication with said inflatable balloon interior and said distal inflatable tip balloon is adapted and configured to shift between a first generally collapsed position and a second generally expanded position such that when in the second position a portion of an exterior surface of said distal inflatable tip balloon defines a second leading edge that aligns with said first tapered leading edge to aid in crossing a stent or vessel obstruction without said leading edge catching on a stent strut or vessel obstruction.
 2. A catheter tip assembly as recited in claim 1, wherein said assembly includes a distal inflation lumen in fluid communication with said inflatable balloon interior and in fluid communication with said distal inflatable tip balloon interior.
 3. A catheter tip assembly as recited in claim 2, wherein said assembly includes a valve operably disposed within said distal inflation lumen.
 4. A catheter tip assembly as recited in claim 3, wherein said valve is a oneway valve, wherein said one-way valve allows a substantially greater rate of flow from said inflatable balloon to said distal inflatable tip balloon than from said distal inflatable tip balloon to said inflatable balloon.
 5. A catheter tip assembly as recited in claim 2, further comprising means for slowly releasing fluid from said distal inflatable tip balloon.
 6. A catheter tip assembly as recited in claim 4, further comprising an elongate valve control member coupled to said one-way valve.
 7. A catheter tip assembly as recited in claim 6, wherein said elongate valve control member extends through said elongate tubular member and can be pulled proximally to open said valve, wherein said valve is biased to close.
 8. A catheter tip assembly as recited in claim 6, wherein said elongate valve control member extends through said elongate tubular member and can be pulled proximally to open said valve, and can be pushed distally to close said valve.
 9. A method for advancing a therapeutic catheter across a stent placed within a body vessel comprising the steps of: providing a catheter including an elongate tubular member having a proximal end, a distal end, and a guide wire receiving lumen and an inflation lumen extending therethrough, an inflatable balloon disposed proximate said distal end of said elongate tubular member, said inflatable balloon having a maximum inflated radial extent, wherein a distal portion of said elongate tubular member extends distally beyond said inflatable to form a catheter tip which defines a leading edge for crossing a vessel obstruction or placed stent, wherein said inflatable balloon interior is in fluid communication with said inflation lumen, a distal inflatable member disposed distal of said balloon, wherein said distal inflatable member has an interior in fluid communication with said balloon interior, wherein said distal inflatable member has a maximum inflated radial extent that is less than said balloon maximum inflated radial extent, and a one-way valve in fluid communication with, and disposed between, said inflatable balloon interior and said distal inflatable member, wherein said one-way valve allows a substantially greater rate of flow from said balloon to said distal inflatable member than from said distal inflatable member to said balloon; advancing said catheter into a body vessel; providing inflation fluid to said inflatable balloon; inflating said inflatable balloon and said distal inflatable member, such that said catheter distal region is radially expanded; allowing said inflatable balloon to at least partially deflate; and advancing said catheter distal inflatable member through said stent. 